Antennas that use microstrip lines as antennas have been proposed in prior art (for example, refer to Japanese Laid-open Patent Publication No. 2014-090291). A multilayered transmission line plate is disclosed, for example, in Japanese Laid-open Patent Publication No. 2014-090291 includes a multilayered plate formed by stacking a first conductive layer, a first dielectric layer, a second conductive layer, a second dielectric layer, and a third conductive layer, one on top of the other in this order, wherein the second conductive layer forms a microstrip line which functions as a feed line. One or more patch conductors are formed on the third conductive layer, and the third conductive layer with such patch conductors formed thereon is disposed so as to partially overlap the second conductive layer when the plane of the multilayered plate is viewed from the top.